The OSI model, as shown on FIG. 1 and as standardized by the ISO organization, defines a networking framework for implementing communication means in seven layers.
As the layers 1 to 4 are in charge of the transport of the data over a given communication medium, layers 5 to 7 are used to allow different applications to communicate independently of the communication infrastructure used.
In terms of video switching, current video routers in the production environment shall be compliant with the SMPTE practice RP168 which defines a switching point and area such that the effects of any signal discontinuity in the chain are minimized, regardless of whether the interface is carrying an uncompressed television signal or a data signal.
Furthermore, all connected equipments are synchronized in phase and frequency thanks to a dedicated signal usually named “Genlock” or “Black Burst”. As an example, the FIG. 2 shows the standardized format of the analogical Genlock signal.
From a video production operations point of view, in a studio, the director, thanks to action on various key of the video switcher, is able to control the video switching from different sources (camera, server, tape, etc.) to different destinations (DVE, monitor, production output, etc.), at a top A/V unit accuracy.
The underlying process, based on the ability of the video router to switch different video sources at top A/V unit accuracy, involves also a control/command step between the video switcher manipulating by the director and the video router, to provide features like                List of available sources        Accurate time indication when to switch from one video to another        Duplication of one video on a set of output,        Etc.        
Lastly, such a service like video switching relies on a deep knowledge from the equipment of the structure of the manipulated essence to be able to determine accurate point and area in the stream.
IT network communication routing and switching operations are handled by two different kinds of network equipments:                Network router:        Routers are network devices that enable to propagate traffic over IP network. This functionality assesses that they are able to process OSI layer-3 information so as to be aware of logical address information. This is the mechanism called “routing”.        A router has a routing table that indicates, for a particular portion of logical addresses, where to route this traffic. Therefore, when a packet enters the router, its logical address is extracted and applied to the routing table to find the port where the packet must be forwarded.        Network switch        Switches are networks equipments that forward traffic on information contained in the layer-2 header. This is what is called “forwarding”, in opposition to “routing” that defines operations on layer-3 information.        Switches only forward traffic to the addressee. This is done by a forwarding table that associates a hardware address to a one of its port. On the receiving of a frame, the layer-2 header gives the hardware address and thus an associated entry in the forwarding table. The switch knows on which port to forward the frame.        
Nevertheless, neither IT network routers nor IT network switches are designed to handle data related to layers upper than the OSI layer-4.